arXiv subjects

Wang Mao

Publications and source records attributed to Wang Mao.

5 recordsLinked to original sources

arXiv2017

Experimental Study of residual radioactivity induced in SFC Electrostatic Deflector

Electrostatic Deflector, one of the key components of SFC accelerator at IMP, is easily activated in the long-term running of HIRFL due to the bombardment with losing ions. The level of residual radioactivity induced in main components and dust contained in the electrostatic deflector enclosure have been investigated using gamma-ray spectrometry and Fluke 451p ionization chamber. The results indicate that the activated electrostatic deflector represent a significant radiological hazard for workers during maintenance operation, and the waste disposal difficulties should be encountered after decommissioning.

physics.ins-det↗

arXiv2017

Study of the neutron dose equivalent at the HIRFL deep tumor therapy terminal

The secondary neutron fields at the deep tumor therapy terminal at HIRFL (Heavy Ion Research Facility in Lanzhou) were investigated. The distributions of neutron ambient dose equivalent were measured with a FHT762 Wendi-II neutron ambient dose equivalent meter as the 12C ions with energies of 165, 207, 270, and 350 MeV/u bombarded on thick tissue-like targets. The thickness of targets used in experiments is larger than the range of the carbon ions. The neutron spectra and dose equivalent is simulated by using FLUKA code, and the results agree well with the experimental data. The experiment results showed that the neutron dose produced by fragmentation reactions in tissue can be neglected in carbon-ion therapy, even considering their enhanced biological effectiveness. These results are also valuable for radiation protection, especially in the shielding design of high energy heavy ion medical machines.

physics.med-ph↗

arXiv2015

Study on neutron radiation field of carbon ions therapy

Carbon ions offer significant advantages for deep-seated local tumors therapy due to their physical and biological properties. Secondary particles, especially neutrons caused by heavy ion reactions should be carefully considered in treatment process and radiation protection. For radiation protection purposes, the FLUKA Code was used in order to evaluate the radiation field at deep tumor therapy room of HIRFL in this paper. The neutron energy spectra, neutron dose and energy deposition of carbon ion and neutron in tissue-like media was studied for bombardment of solid water target by 430MeV/u C ions. It is found that the calculated neutron dose have a good agreement with the experimental date, and the secondary neutron dose may not exceed one in a thousand of the carbon ions dose at Bragg peak area in tissue-like media.

physics.med-ph↗

arXiv2014

Probability density derivation and analysis of SINR in massive MIMO systems with MF beamformer

In massive MIMO systems, the matched filter (MF) beamforming is attractive technique due to its extremely low complexity of implementation compared to those high-complexity decomposition-based beamforming techniques such as zero-forcing, and minimum mean square error. A specific problem in applying these techniques is how to qualify and quantify the relationship between the transmitted signal, channel noise and interference. This paper presents detailed procedure of deriving an approximate formula for probability density function (PDF) of the signal-to-interference-and-noise ratio (SINR) at user terminal when multiple antennas and MF beamformer are used at the base station. It is shown how the derived density function of SINR can be used to calculate the symbol error rate of massive MIMO downlink. It is confirmed by simulation that the derived approximate expression for PDF is consistent with the simulated PDF in medium-scale and large-scale MIMO systems.

cs.NI↗

arXiv2011

A Frequency-domain Compensation Scheme for IQ-Imbalance in OFDM Receivers

A pilot pattern across two OFDM symbols with special structure is devised for channel estimation in OFDM systems with IQ imbalance at receiver. Based on this pilot pattern, a high-efficiency time-domain (TD) least square (LS) channel estimator is proposed to significantly suppress channel noise by a factor N/(L+1) in comparison with the frequency-domain LS one in [1] where N and L+1 are the total number of subcarriers and the length of cyclic prefix, respectively. Following this, a low-complexity frequency-domain (FD) Gaussian elimination (GE) equalizer is proposed to eliminate IQ distortion by using only 2N complex multiplications per OFDM symbol. From simulation, the proposed scheme TD-LS/FD-GE using only two pilot OFDM symbols achieves the same bit error rate (BER) performance under ideal channel knowledge and no IQ imbalances at low and medium signal-to-noise ratio (SNR) regions whereas these compensation schemes including FD-LS/Post-FFT LS, FD-LS/Pre-FFT Corr, and SPP/Pre-FFT Corr in [1] require about twenty OFDM training symbols to reach the same performance where A/B denotes compensation scheme with A being channel estimator and B being equalizer.

cs.NI↗